This invention generally relates to surface marking devices adapted to mark a guide line or stripe upon the surface of a road or pavement. More specifically, the present invention relates to line marking devices having adjustable means for installation of parking lines and traffic markings of varying width.
Line marking devices in the prior art utilize a paint spray mechanism generally including a paint tank and a pressurized air tank interconnected by suitable coupling means. Feeder lines connected to the paint tank and a spray nozzle permit the delivery of a pressurized air and paint mixture to the surface of the road or pavement. U.S. Pat. No. 1,709,091 to Nissly discloses such road marking apparatus. Therein a paint receptacle tank and compressed fluid receptacle tank are interconnected by means of pipe and valve assemblies to permit ejection of a paint spray through a nozzle head. The nozzle head is formed in a prescribed width and length corresponding to the desired width of surface marking, the width of paint imparted to the road surface being limited by the walls of the substantially rectangular (in plan) nozzle head.
Adjustable means to limit a guide line or stripe to varying widths is achieved in the surface marking devices of the prior art by use of various paint spray baffling means disposed adjacent to the surface of the road or pavement to be marked. In U.S. Pat. No. 1,998,502 to Glasgow, such paint spray baffling means is embodied in a pair of rotatable discs held in spaced apart relationship to each side of the spray nozzle. The discs rotate over the surface of the road and are provided with screw adjustment means that permit the distance between them to be axially adjusted along the support hub. The paint spray mechanism delivers a spray of paint, the spread of paint and thus the width of the resulting guide line or stripe being limited by the spaced apart relationship of the discs. U.S. Pat. No. 1,999,563 to Glasgow discloses substantially similar means for limiting the width of the painted guide line or stripe. Rotatable discs held in spaced apart relationship to each side of the spray nozzle are threadedly attached to sleeve assemblies mounted on the support hub. By means of their threaded support, the discs may be spaced apart at various distances.
U.S. Pat. No. 2,251,719 to Sapp likewise discloses laterally adjustable discs which rotate along the road surface defining the width of the guide line or stripe to be marked. In U.S. Pat. No. 2,812,211 to Gardner a unitary spray tank is utilized providing a paint receptacle tank capable of having air pressure developed therein by means of a manual pump mechanism. Developed air pressure forces the paint from the spray tank through an attached nozzle to deliver a spray of paint onto the surface to be marked. A rectangular box shield embraces the spray nozzle, the side portions of the shield retaining the spray laterally to define the width of paint transmitted to the surface. U.S. Pat. No. 2,964,245 to Anderson et al. describes a stripe painting apparatus for use in connection with the conventional paint supply and compressed air assembly. The invention therein disclosed includes vertically extending paint shield plates which limit the lateral spray of paint from the nozzle to provide for a painted stripe of predetermined width. The paint shield plates are slidably mounted to a transverse shaft and attached to lateral-adjustment control means comprising a cable and pulley assembly which permits the distance between shield plates to be adjusted to varied spaced apart relationships. A further cable and pulley assembly is also disclosed which permits the nozzle to be adjusted to predetermined vertical positions. U.S. Pat. No. 3,050,260 to Macrae et al. discloses a paint spray carrier for use with the conventional paint supply and compressed air supply spray paint assembly. The carrier includes paint guides laterally spaced to each side of the spray nozzle comprising vertically extending rectangular plates which engage the surface to be marked at the plate's lower edge. Adjustment means is provided to position the nozzle at a distance above the surface proportionate to the spacing of the paint guides so that the spray of paint ejected from the nozzle will be appropriately confined within the paint guides.
The various paint spray baffling means as disclosed in the prior art are required as a result of the manner in which conventional paint spray mechanisms operate. Paint spray mechanisms which utilize in combination a pressurized air supply and paint supply deliver a dispersed mixture of air and paint to the surface to be marked. Baffling means serve to concentrate the paint spray. The volume of air in the delivered spray also reduces the amount of paint marking the surface, necessitating a greater volume of spray to be delivered for a desired cover than would be required to paint the same area in the absence of air in the spray. Such paint spray mechanisms thus require the operator to move along the surface to be marked at a slower pace to achieve the desired paint marking of the surface. A paint spray comprising air and paint is also more susceptible to environmental conditions, e.g. wind. Therefore, the provision of a surface marking device to mark a guide line or stripe upon the surface of a road or pavement which facilitates efficient use of paint is desirable. Also, a paint spray mechanism which permits a more quickly-paced marking of guide lines or stripes upon the surface of a road or pavement provides additional utility not presently realized by the paint spray apparatus of the prior art. It is also desirable to provide a paint spray mechanism to mark guide lines or stripes upon the surface of a road or pavement that is less sensitive to environmental conditions.